Our Deep Muscle Relief add-on uses a professional strength heating & cooling gel in combination with hot towels to offer the ultimate enhancement to pain relief. If you have a problem area that is really causing you pain, this is an excellent add-on for adding targeted pain relief. The gel is very strong, but safe for most skin types. After massaging the targeted area, your therapist will use hot towels and apply the gel which will assist you with extra pain relief for hours to come.